1. Field of the Invention
The invention relates to a feeding device for closed shaft furnaces connected to a gas-extracting device, in particular for low shaft furnaces for melting steel scrap, having a transporting device, which leads to the head of the upper furnace vessel and is integrated at least partially in the furnace atmosphere, and a distributing device for distributing the charge.
2. Discussion of the Prior Art
German Patent 17 58 842 discloses a feeding device which is intended for gas-tight electric furnaces and in the case of which each electrode is assigned feeding tubes above which there is provided a ring which is connected to a rotary drive and to a conveying belt for transporting the charge. In their top part, the feeding tubes are designed as bunkers over which there are provided hoppers which are arranged rotatably via a plurality of running wheels on a ring supported on a circular rail. The ring is closed off in a gas-tight manner by cup seals.
This device, of complex design, only allows the stock level to be charged at certain points in dependence on the number of bunkers.
German Patent 33 14 943 discloses an apparatus for feeding electrothermal smelting furnaces in which annular chambers are arranged concentrically around each electrode, having at least one closable opening leading to the furnace vessel, a concentric inner wall and a concentric outer wall connected thereto. It is possible for the two walls to be rotated relative to the electrode.
This complicated feeding apparatus does not allow the charge to be distributed uniformly in relation to the furnace head as a whole.
Furthermore, German reference DE 44 07 861 C1 discloses a feeding apparatus for closed arc furnaces in which the charge is charged uniformly and concentrically to the annular chamber provided around a concentric main furnace axis. For this purpose, use is made of a traveling mechanism which has switchable lifting magnets.
The disadvantage with this apparatus is the need for an exclusively metallic charge which can be transported by the magnetic conveyor.
The object of the present invention is to provide a feeding device for closed shaft furnaces which, by straightforward design means, ensures that even a non-metallic charge is supplied reliably to any desired points of the stock level in the furnace.
The invention provides, in the furnace head, a carousel which is constructed from shutter elements and is guided rotatably on a path in the furnace head. The carousel can be charged by a conveying device. One supply point is sufficient for charging the carousel. In this case, the carousel may be charged uniformly or else with predetermined quantities and/or materials.
For charging purposes, the carousel is moved into position and emptied by specific activation of the individual shutter elements.
In this case, the individual shutter elements may be designed as tines which taper in the direction of their tip. In another advantageous configuration, the shutter elements are dimensioned, as segments of a ring, with a width B, where B=xc2xc to {fraction (1/16)} of the circumference of the furnace head, and with a depth c of c=0.1 to 1.0xc3x97R, where R=radius of the furnace head.
Rotary shutter elements and damping elements are provided for damping the impact when the charge comes into contact with the individual shutters of the carousel. These dampers may be independent elements on which the shutters are supported; however, they may also be parts of the shutter-retaining levers.
For straightforward actuation of the shutter elements, the latter are provided, in the region of the tilting spindle, with levers which are connected to actuators. Proposed actuators are piston/cylinder units or rotary drives.
The carousel according to the invention can be used for any desired shaft furnaces including low shaft furnaces which have electrodes for melting the charge. It is possible for these electrodes to project into the furnace interior without protection or else to be enclosed by a central tube.
In the case of electric arc furnaces with a central tube, it is proposed for the ends of the shutter elements to be supported on supporting elements fastened on the central tube. In an advantageous configuration, these supporting elements may be connected in a form-fitting manner to the shutter elements, for example may be configured as rotary levers. During the operation of charging the carousel, the individual shutters are arrested and released before opening.
According to the invention, the rotary spindle of the shutters may be routed in accordance with the outer ring of the carousel. However; the rotary spindles may also be oriented radially in relation to the main furnace axis. In the latter case, the shutter elements may be configured as double-wing shutters.
Piston/cylinder units or rotary drives are proposed for actuating the shutters. Damping elements are used in each case for absorbing the impact. Use may be made of back-coupling means in this case for the rotary drives. Furthermore, in the case of the rotary drives, the connection to the individual shutters may take place via cable elements.
The individual drives of the shutters are connected to a measuring and regulating device, the latter being connected in control terms to a stock-level measuring means, with the result that the stock level is charged in a manner appropriate for consumption.